Rodent1.java

import java.util.*;

class RandomRodentGenerator1 {
	private Random rand = new Random();
	public Rodent next() {
		switch(rand.nextInt(3)) {
			default:
			case 0: return new Mouse();
			case 1: return new Rat();
			case 2: return new Squirrel();			
		}
	}
 }

abstract class Rodent {
	private String name = "Rodent";
	abstract protected void eat(); 
	abstract protected void run(); 
	abstract protected void sleep();
	abstract public String toString(); 
}

class Mouse extends Rodent {
	private String name = "Mouse";
	protected void eat() { System.out.println("Mouse.eat()"); }
	protected void run() { System.out.println("Mouse.run()"); }
	protected void sleep() { System.out.println("Mouse.sleep()"); }
	public String toString() { return name; }
}

class Rat extends Rodent {
	private String name = "Rat";
	protected void eat() { System.out.println("Rat.eat()"); }
	protected void run() { System.out.println("Rat.run()"); }
	protected void sleep() { System.out.println("Rat.sleep()"); }
	public String toString() { return name; }
}

class Squirrel extends Rodent {
	private String name = "Squirrel";
	protected void eat() { System.out.println("Squirrel.eat()"); }
	protected void run() { System.out.println("Squirrel.run()"); }
	protected void sleep() { System.out.println("Squirrel.sleep()"); }
	public String toString() { return name; }
}

public class Rodent1 {
	private static RandomRodentGenerator1 gen = new RandomRodentGenerator1();
	public static void main(String[] args) {
		// Error: cannot instantiate abstract class:
		// Rodent x = new Rodent();
		// But OK to create array to be downcast to derived objects:
		Rodent[] rodents = new Rodent[10];
		for(Rodent r : rodents) {
			r = gen.next();
			System.out.println(r + ": ");
			r.eat();
			r.run();
			r.sleep();			
		}		
	}
}